Conventional pipe joints as a whole are of simple structure, that is, female thread is cut in the interior of a joint while male thread is on the surface of the end of pipe-to-be-connected. Having the threaded end sealed with plastic tape, the pipe is then screwed into the joint, and a wrench or spanner is used to tighten the joint. As wrenches and spanners, however, are not common tools for ordinary people, such work has general become exclusive for plumbers and is difficult to be simplified. Moreover, inconvenience during this process is encountered as thread cutting, tape sealing and spanner tightening are to be proceeded in the field to match the actual lining. In response to these problems, people have invented fast-assembled joints to eliminate difficulties and inconveniences caused. Some of these kinds of fast-assembled joints are even being applied to water pipe connections resulted in simplified and prompt performance. However, the high cost both in material and energy in such known joints are not economical.